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Alkylation

About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.


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Journal ArticleDOI
Shu-Yu Zhang1, Qiong Li1, Gang He1, William A. Nack1, Gong Chen1 
TL;DR: Evidence strongly suggests that the functionalization of the palladacycle with secondary alkyl iodides proceeds via a rarely precedented concerted oxidative addition pathway.
Abstract: We report a method for the monoselective alkylation of ortho-C–H bonds of N-quinolyl benzamides with both primary and secondary alkyl halides under palladium catalysis. With promotion by NaHCO3 and (BnO)2PO2H or (PhO)2PO2H, symmetric benzamide substrates can be selectively ortho-alkylated to give either mono- or dialkylated products by simply adjusting the amount of NaHCO3 applied. The use of phosphate notably improves the alkylation yield, although it may not be directly involved in C–H palladation or the subsequent functionalization step. Kinetic isotope effect studies indicate that C–H palladation is not the rate-limiting step. Examination of the reactions of an isolated palladacycle intermediate with both cis- and trans-4-methylcyclohexyl iodides revealed surprising stereoretentive couplings of these alkyl iodides. This evidence strongly suggests that the functionalization of the palladacycle with secondary alkyl iodides proceeds via a rarely precedented concerted oxidative addition pathway.

139 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of a complete triad of Group 4 carbenes is reviewed and their reaction chemistry demonstrating nucleophilic alkylation, Lewis acidity of the metal, 1,2 addition across the MC carbene bond and [2+2] cycloaddition across this double bond.

139 citations

Journal ArticleDOI
TL;DR: The most active members in this series of compounds were found to be 8-ethyl- and 8-vinyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acids, both of which are more active in vitro and in vivo against gram-negative bacteria than piromidic acid.
Abstract: The preparation and antibacterial activity of a series of the title compounds (21-73) are described. These compounds were prepared from the 2-methylthio derivatives 2 and 3 via the 2-methylthio-8-substituted compounds 4-20; compounds 4-20 easily underwent displacement reactions with a variety of piperazines to afford 2-(4-substituted or unsubstituted 1-piperazinyl) derivatives 21-56, of which 21, 22, 27 and 51 with unsubstituted piperazinyl group at position 2 are converted subsequently into 57-73 by alkylation, acylation, sulfonylation, or addition of isocyanates to the piperazine nitrogen. The hexahydro-1H-1,4-diazepinyl analog 74 was also prepared. The most active members in this series of compounds were found to be 8-ethyl- and 8-vinyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acids (22 and 51), both of which are more active in vitro and in vivo against gram-negative bacteria, including Pseudomonas aeruginosa, than piromidic acid (1). Structure-activity relationships are discussed.

139 citations

Journal ArticleDOI
TL;DR: The availability of methyl tert- tert-butyl ether and tert-amyl methyl ether allows tert -butyl and tert -amyl derivatives of phenolic substances to be produced with the attendant advantages as discussed by the authors.
Abstract: Cationic ion-exchange resins, particularly the macroporous variety, are versatile catalysts which offer several advantages over the homogeneous acid catalysts with respect to corrosion, product recovery, selectivity, etc. In some cases, such as etherification of phenols/naphthols with isobutylene/isoamylene, resin catalysts allow the reaction to occur, but the homogeneous catalysts fail. A noteworthy development has been the use of distillation column reactors (DCR) where the exothermicity of the reaction is usefully employed and the resin inventory, for a specified level of conversion and productivity, can be significantly reduced. The availability of methyl- tert -butyl ether and tert -amyl methyl ether allows tert -butyl and tert -amyl derivatives of phenolic substances to be produced with the attendant advantages. The removal of low concentrations of substances like formaldehyde in aqueous medium offers new opportunities for resin catalysts and methylal formation with methanol in DCR has been realized in bringing down formaldehyde concentration from 1 to 2% (wt) to as low as 0.02%. Resin catalysts are useful for oligomerization of olefins like isobutylene, isoamylene, α-methyl styrene, etc.; cross-dimerization of olefins for making precursors for synthetic musks, can also be advantageously carried out. The alkylation of dissolved polyvinyl phenol with isobutylene, with resin catalysts is interesting in several ways. Many close-boiling substances, such as isomeric and non-isomeric phenolic substances, can be separated through selective reactions based on resin catalysts.

139 citations

Journal ArticleDOI
TL;DR: N-Benzyl-N-(3-methyl-2-pyridyl)amine 1 reacts with various alkenes via sp3 C-H bond cleavage by catalytic Ru3(CO)12 to give the corresponding alkylated products.

139 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023652
20221,161
2021561
2020516
2019630
2018631